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JAEA Reports

Practical guide on soil sampling, treatment, and carbon isotope analysis for carbon cycle studies

Koarashi, Jun; Atarashi-Andoh, Mariko; Nagano, Hirohiko*; Sugiharto, U.*; Saengkorakot, C.*; Suzuki, Takashi; Kokubu, Yoko; Fujita, Natsuko; Kinoshita, Naoki; Nagai, Haruyasu; et al.

JAEA-Technology 2020-012, 53 Pages, 2020/10

JAEA-Technology-2020-012.pdf:3.71MB

There is growing concern that recent rapid changes in climate and environment could have a significant influence on carbon cycling in terrestrial ecosystems (especially forest ecosystems) and could consequently lead to a positive feedback for global warming. The magnitude and timing of this feedback remain highly uncertain largely due to a lack of quantitative understanding of the dynamics of organic carbon stored in soils and its responses to changes in climate and environment. The tracing of radiocarbon (natural and bomb-derived $$^{14}$$C) and stable carbon ($$^{13}$$C) isotopes through terrestrial ecosystems can be a powerful tool for studying soil organic carbon (SOC) dynamics. The primary aim of this guide is to promote the use of isotope-based approaches to improve our understanding of the carbon cycling in soils, particularly in the Asian region. The guide covers practical methods of soil sampling; treatment and fractionation of soil samples; preparation of soil samples for $$^{13}$$C (and stable nitrogen isotope, $$^{15}$$N) and $$^{14}$$C analyses; and $$^{13}$$C, $$^{15}$$N, and $$^{14}$$C measurements by the use of isotope ratio mass spectrometry and accelerator mass spectrometry (AMS). The guide briefly introduces ways to report $$^{14}$$C data, which are frequently used for soil carbon cycling studies. The guide also reports results of a case study conducted in a Japanese forest ecosystem, as a practical application of the use of isotope-based approaches. This guide is mainly intended for researchers who are interested but are not experienced in this research field. The guide will hopefully encourage readers to participate in soil carbon cycling studies, including field works, laboratory experiments, isotope analyses, and discussions with great interest.

Journal Articles

Vertical distributions of Iodine-129 and iodide in the Chukchi Sea and Bering Sea

Miwa, Kazuji; Obata, Hajime*; Suzuki, Takashi

Journal of Nuclear Science and Technology, 57(5), p.537 - 545, 2020/05

 Times Cited Count:1 Percentile:62.32(Nuclear Science & Technology)

This study investigated the vertical distribution of Iodine-129 ($$^{129}$$I) which is mainly produced by European nuclear reprocessing plants in the Chukchi Sea and Bering Sea. $$^{129}$$I was found to be distributed almost uniformly in fallout level, and an increasing in $$^{129}$$I concentration levels caused by high $$^{129}$$I water inflow from the Atlantic Ocean was not observed. Additionally, we revealed the vertical distribution of iodide, one chemical form of iodine, from the Bering Shelf area to the Chukchi Sea for the first time. The increasing tendency of iodide near sea bottom was observed.

Journal Articles

Penetration of $$^{129}$$I released from Fukushima Daiichi Nuclear Power Plant accident in the western North Pacific Ocean

Suzuki, Takashi; Otosaka, Shigeyoshi; Kuwabara, Jun; Kawamura, Hideyuki; Kobayashi, Takuya

JAEA-Conf 2018-002, p.103 - 106, 2019/02

To investigate the dynamics of radionuclides in the ocean released by the accident at Fukushima Daiichi Nuclear Power Plant (1F), vertical distributions of $$^{129}$$ I at three stations in the western North Pacific was revealed. The 1F accident-derived $$^{129}$$ I existed within the mixed layer at 3 stations. The maximum layer of the 1F accident-derived $$^{129}$$ I existed at the depth of 370 m - 470 m at the most southern station. Considering the dissolved oxygen concentration and the current velocity arround the station, the maximum layer of the 1F accident-derived $$^{129}$$ I would be fromed that $$^{129}$$I which existed in the surface seawater at other area of observation point was carried to the depth of 370 m - 470 m by the fast downward flow.

Journal Articles

Distribution and fate of $$^{129}$$I in the seabed sediment off Fukushima

Otosaka, Shigeyoshi; Sato, Yuhi*; Suzuki, Takashi; Kuwabara, Jun; Nakanishi, Takahiro

Journal of Environmental Radioactivity, 192, p.208 - 218, 2018/12

AA2017-0744.pdf:1.17MB

 Times Cited Count:6 Percentile:55.71(Environmental Sciences)

From August 2011 to October 2013, the concentration of iodine-129 ($$^{129}$$I) in the seabed sediment collected from 26 stations located within 160 km from the Fukushima Daiichi Nuclear Power Plant was estimated. The concentrations of $$^{129}$$I in seabed sediment off Fukushima in 2011 ranged between 0.02 and 0.45 mBq/kg. Although iodine is a biophilic element, the accident-derived radioiodine negligibly affects the benthic ecosystem. Until October 2013, a slightly increased activity of $$^{129}$$I in the surface sediment in the shelf-edge region (bottom depth: 200-400 m) was observed. The increase of the $$^{129}$$I concentrations in the shelf-edge sediments was affected by the (1) transport of $$^{129}$$I-bound particles from the land through rivers and (2) re-deposition of $$^{129}$$I desorbed from the contaminated coastal sediment to the shelf-edge sediments, which were considered to be dominant processes.

Journal Articles

Vertical distribution of $$^{129}$$I released from the Fukushima Daiichi Nuclear Power Plant in the Kuroshio and Oyashio current areas

Suzuki, Takashi; Otosaka, Shigeyoshi; Kuwabara, Jun; Kawamura, Hideyuki; Kobayashi, Takuya

Marine Chemistry, 204, p.163 - 171, 2018/08

 Times Cited Count:0 Percentile:100(Chemistry, Multidisciplinary)

To investigate the penetration of radionuclides released from Fukushima Daiichi Nuclear Power Plant (FDNPP), depth profiles were revealed at Kuroshio current, transition, and Oyashio current areas. The FDNPP-derived $$^{129}$$I was found in surface layer at Oyashio current and transition areas and in sub-surface layer at Kuroshio current area. Moreover, it was found that the FDNPP-derived $$^{129}$$I/$$^{134}$$Cs ratios in the Oyashio current and transition areas were higher than that in the FDNPP reactor. The higher FDNPP-derived $$^{129}$$I/$$^{134}$$Cs ratios suggest three potential mechanisms for the migration of radionuclides in the environment: (1) radioiodine was released more easily than radiocesium by the FDNPP accident, (2) $$^{129}$$I was supplied from the atmosphere by re-emitted $$^{129}$$I from contaminated areas around Fukushima, (3) leaked water that removed radiocesium reached the sampling stations. The FDNPP-derived $$^{129}$$I in sub-surface layer would be transported by the meander of the Kuroshio Extension current.

Journal Articles

Vertical distributions of global fallout $$^{137}$$Cs and $$^{14}$$C in a Japanese forest soil profile and their implications for the fate and migration processes of Fukushima-derived $$^{137}$$Cs

Koarashi, Jun; Atarashi-Andoh, Mariko; Amano, Hikaru*; Matsunaga, Takeshi

Journal of Radioanalytical and Nuclear Chemistry, 311(1), p.473 - 481, 2017/01

 Times Cited Count:12 Percentile:9.74(Chemistry, Analytical)

Vertical distributions of global fallout $$^{137}$$Cs and $$^{14}$$C were investigated in a Japanese forest soil in 2001. Even 38 years after the fallout, $$^{137}$$Cs was still observed mostly in the uppermost 5 cm. A preferential accumulation of $$^{137}$$Cs was found in a 1-cm-thick transition layer between organic-rich A and underlying B horizons. This unique observation indicated that $$^{137}$$Cs migrated through the A horizon at a rate of 0.20% y$$^{-1}$$ and the transition layer acted as a barrier for $$^{137}$$Cs migration to deeper layers. The vertical distributions of $$^{137}$$Cs and $$^{14}$$C were significantly correlated, suggesting a coupled downward migration of $$^{137}$$Cs and organic matter on a time scale of decades, along the same physical pathways.

Journal Articles

Status of JAEA-AMS-MUTSU

Kuwabara, Jun; Kinoshita, Naoki; Tobinai, Kazuhito; Matsuno, Satoru; Oyokawa, Atsushi; Seki, Takeo; Yabuuchi, Noriaki

Dai-28-Kai Tandemu Kasokuki Oyobi Sono Shuhen Gijutsu No Kenkyukai Hokokushu, p.77 - 79, 2015/12

A Tandetron AMS system (JAEA-AMS-MUTSU) at Mutsu Office, Aomori Research and Development Center, Sector of Decommissioning and Radioactive Waste Management, JAEA, installed in 1997, has composed of 3 MV tandem accelerator and two beam lines (carbon and iodine). Status of the JAEA-AMS-MUTSU and trouble of ion source caused by deterioration of optical fiber cable are reported.

Journal Articles

Status of JAEA-AMS-MUTSU

Kuwabara, Jun; Kinoshita, Naoki; Hamada, Akio; Tobinai, Kazuhito; Seki, Takeo

Dai-27-Kai Tandemu Kasokuki Oyobi Sono Shuhen Gijutsu No Kenkyukai Hokokushu, p.27 - 30, 2015/03

A Tandetron AMS system (JAEA-AMS-MUTSU) at Mutsu Office, Aomori Research and Development Center, Sector of Decommissioning and Radioactive Waste Management, JAEA, installed in 1997, has composed of 3 MV tandem accelerator and two beam lines (carbon and iodine). Status of the JAEA-AMS-MUTSU and trouble cases about ion source are reported.

Journal Articles

Iodine-129 concentration in seawater near Fukushima before and after the accident at the Fukushima Daiichi Nuclear Power Plant

Suzuki, Takashi; Otosaka, Shigeyoshi; Kuwabara, Jun; Kawamura, Hideyuki; Kobayashi, Takuya

Biogeosciences, 10(6), p.3839 - 3847, 2013/06

 Times Cited Count:20 Percentile:36.85(Ecology)

no abstracts in English

Journal Articles

Distribution of iodine-129 in the northwestern North Pacific Ocean between Jan and Feb 2012

Suzuki, Takashi; Otosaka, Shigeyoshi; Kuwabara, Jun

Dai-15-Kai AMS Shimpojiumu Hokokushu, p.49 - 52, 2013/03

no abstracts in English

Journal Articles

Concentration of iodine-129 in surface seawater at subarctic and subtropical circulations in the Japan Sea

Suzuki, Takashi; Otosaka, Shigeyoshi; Togawa, Orihiko

Nuclear Instruments and Methods in Physics Research B, 294, p.563 - 567, 2013/01

 Times Cited Count:4 Percentile:60.53(Instruments & Instrumentation)

no abstracts in English

Journal Articles

Seasonal patterns and control factors of CO$$_{2}$$ effluxes from surface litter, soil organic carbon, and root-derived carbon estimated using radiocarbon signatures

Atarashi-Andoh, Mariko; Koarashi, Jun; Ishizuka, Shigehiro*; Hirai, Keizo*

Agricultural and Forest Meteorology, 152, p.149 - 158, 2012/01

 Times Cited Count:27 Percentile:15.19(Agronomy)

Radiocarbon ($$^{14}$$C) signature was used to partition soil respiration in a cool-temperate deciduous forest. Heterotrophic respiration strongly correlated with soil temperature, but the magnitude of the response to soil temperature was different between SOC decomposition and litter decomposition. Autotrophic respiration appeared to correlate strongly with the phenology index rather than soil temperature. The information on the seasonal change about the contribution ratio of each source to the soil respiration is essential to understand the intrinsic temperature sensitivity of each source and the other factors controlling soil respiration.

Journal Articles

Status of JAEA-AMS-MUTSU at 2010-2011

Kabuto, Shoji; Kinoshita, Naoki; Tanaka, Takayuki; Kuwabara, Jun; Seki, Takeo

Dai-24-Kai Tandemu Kasokuki Oyobi Sono Shuhen Gijutsu No Kenkyukai Hokokushu, p.9 - 12, 2011/07

A Tandetron Accelerator Mass Spectrometer (AMS) manufactured by High Voltage Engineering Europa in Netherlands had been set up at the Mutsu office of Aomori Research and Development Center, Japan Atomic Energy Agency (JAEA) in 1997. This AMS features 3 MV Tandetron accelerator and two independence beamlines for $$^{14}$$C and $$^{129}$$I measurement. In this report, we describe the summary of the current status at 2010-2011.

Journal Articles

Current status of $$^{14}$$C measurement at JAEA-AMS-MUTSU

Tanaka, Takayuki; Kabuto, Shoji; Kinoshita, Naoki; Seki, Takeo

Nagoya Daigaku Kasokuki Shitsuryo Bunsekikei Gyoseki Hokokusho, 22, p.169 - 173, 2011/03

An accelerator mass spectrometry at Mutsu office, Japan Atomic Energy Agency (JAEA AMS MUTSU) was established in 1997 and the routine operation of radiocarbon measurement was started from 1999. The radiocarbon was measured by 1,053 samples in 2010, and the number of radiocarbon measurements reached 10,342 samples since the routine operation. This AMS has adopted the open door policy for the general users from the fiscal year of 2006 and various researches have been in progress by many users. In this presentation, I introduce the current status of JAEA AMS MUTSU.

Journal Articles

Surface concentrations of $$^{129}$$I around the subarctic front in the Japan Sea

Suzuki, Takashi; Otosaka, Shigeyoshi; Togawa, Orihiko

Dai-13-Kai AMS Shimpojiumu Hokokusho, p.69 - 72, 2011/01

no abstracts in English

Journal Articles

Status of JAEA-AMS-MUTSU

Tanaka, Takayuki; Kabuto, Shoji; Kinoshita, Naoki; Suzuki, Takashi; Kuwabara, Jun; Seki, Takeo

Dai-13-Kai AMS Shimpojiumu Hokokusho, p.129 - 132, 2011/01

An accelerator mass spectrometry at Aomori Research and Development Center, JAEA (JAEA-AMS-MUTSU) was established in 1997 and the routine operation of $$^{14}$$C and $$^{129}$$I measurement was started from 1999 and 2003, respectively. This AMS has adopted the open door policy for the general users from the fiscal year of 2006 and various researches have been in progress by many users. In this presentation, we introduce the status of JAEA-AMS-MUTSU. The total number of measurements has increased well for five years after the open door policy excluding in 2008. The reasons for the decrease in 2008 were that we had stopped the operation of AMS for about one and half months because the operation system of AMS was upgraded, and that we could not measure the $$^{14}$$C for several months because the amplifier of detector had broken. We had resolved this trouble and our AMS can measure smoothly both $$^{14}$$C and $$^{129}$$I.

Journal Articles

Status of JAEA-AMS-MUTSU at 2009-2010

Tanaka, Takayuki; Kabuto, Shoji; Kinoshita, Naoki; Suzuki, Takashi; Kuwabara, Jun; Seki, Takeo

Dai-23-Kai Tandemu Kasokuki Oyobi Sono Shuhen Gijutsu No Kenkyukai Hokokushu, p.113 - 116, 2010/11

An accelerator mass spectrometry at Aomori Research and Development Center, JAEA (JAEA-AMS-MUTSU) was established in 1997 and the routine operation of $$^{14}$$C and $$^{129}$$I measurement was started from 1999 and 2003, respectively. This AMS has adopted the open door policy for the general users from the fiscal year of 2006 and various researches have been in progress by many users. In this presentation, we introduce the status of JAEA-AMS-MUTSU in the fiscal year of 2009. The $$^{14}$$C and $$^{129}$$I were measured by 480 and 677 samples in the fiscal year of 2009, respectively. The total number of measurements has decreased by 716 samples from that of the fiscal year of 2008. The reasons for this decrease were that we had stopped the operation of AMS for about one and half months because the operation system of AMS was upgraded, and that we could not measure the $$^{14}$$C for several months because the amplifier of detector had broken. We had resolved this trouble and our AMS can measure smoothly both $$^{14}$$C and $$^{129}$$I.

Journal Articles

Certified reference material IAEA-418; $$^{129}$$I in mediterranean sea water

Pham, M. K.*; Betti, M.*; Povinec, P. P.*; Alfimov, V.*; Biddulph, D.*; Gastaud, J.*; Kieser, W. E.*; L$'o$pez, Guti$'e$rrez, J. M.*; Possnert, G.*; Sanchez-Cabeza, J. A.*; et al.

Journal of Radioanalytical and Nuclear Chemistry, 286(1), p.121 - 127, 2010/10

 Times Cited Count:13 Percentile:28.26(Chemistry, Analytical)

no abstracts in English

Journal Articles

Spatial distribution of $$Delta$$$$^{14}$$C values of organic matter in surface sediments off Saru River in northern Japan, one year after a flood event in 2006

Nagao, Seiya*; Irino, Tomohisa*; Aramaki, Takafumi*; Ikehara, Ken*; Katayama, Hajime*; Otosaka, Shigeyoshi; Uchida, Masao*; Shibata, Yasuyuki*

Radiocarbon, 52(3), p.1068 - 1077, 2010/08

This study discusses the effects of flooding on the spatial distribution of organic matter on the shelf region of off the Saru River, southern part of Hokkaido, Japan, on the basis of the $$Delta$$$$^{14}$$C and $$delta$$$$^{13}$$C values. Surface sediments on the shelf were collected in August 2007, one year after the severe flood in 2006. Suspended particles and sediment of the Saru River were also collected in August 2007 and 2008. The $$Delta$$$$^{14}$$C values of organic matter in the shelf sediments ranged from -665 to -77 per mil. The silt and clay sediments had $$Delta$$$$^{14}$$C values of -240 to -77 per mil, but the sandy sediments ranged from -665 to -388 per mil. The $$Delta$$ values of particulate organic carbon in the Saru River are -292 to -247 per mil at normal flow conditions. These results indicate that surface soil with relatively older organic matter is deposited on the shelf region by the flooding event, and freshly-produced organic matter in sea surface is deposited after the flooding.

Journal Articles

Development of the digestion method of environmental samples by the silver-mediated electrochemical oxidation process for iodine analysis

Kuwabara, Jun

Dai-12-Kai AMS Shimpojiumu Hokokushu, p.112 - 115, 2010/05

In the analysis of the iodine isotope, dry combustion method is used for sample preparation. Depending on the kind of the sample, the iodine remaining situation occurs without volatilizing enough. The silver mediated electrochemical oxidation process was tried to obtain high recovery. Digestion of dried Konbu sample was completed in around 24 hours under 5 V of electric condition. After the digestion, AgI precipitate was obtained by adding sodium sulfite as reductant to the filtered sample solution.

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